Before posing an implant onto a bone, such as during a knee or hip replacement surgery, the bone needs to be prepared. The preparation of the bone includes removing diseased bone, for example, and making additional cuts so that the bone has a shape matching that of an inside of the implant, or drilling holes, placing guides, etc for providing guidance landmarks to an operator. For instance, in knee implant surgery, transverse and frontal cut planes are made to match surfaces of an implant.
Determination of alterations to the bone, of the portions of the bone that need to be removed, of guides to be placed may be done prior to surgery using images of the bone of the patient, in pre-operative planning. The pre-operative planning may help in ensuring the precision and accuracy of the surgery, as bone alterations will influence the fit of the implant onto the bone. For example, a bone that has been improperly cut may lead to improper implant placement, resulting in conditions such as leg length discrepancy, improper gait, premature implant wear, and pain, to name a few.